Implement --sdnotify cmdline option to control sd-notify behavior

--sdnotify container|conmon|ignore
With "conmon", we send the MAINPID, and clear the NOTIFY_SOCKET so the OCI
runtime doesn't pass it into the container. We also advertise "ready" when the
OCI runtime finishes to advertise the service as ready.

With "container", we send the MAINPID, and leave the NOTIFY_SOCKET so the OCI
runtime passes it into the container for initialization, and let the container advertise further metadata.
This is the default, which is closest to the behavior podman has done in the past.

The "ignore" option removes NOTIFY_SOCKET from the environment, so neither podman nor
any child processes will talk to systemd.

This removes the need for hardcoded CID and PID files in the command line, and
the PIDFile directive, as the pid is advertised directly through sd-notify.

Signed-off-by: Joseph Gooch <mrwizard@dok.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/libpod/define/config.go b/libpod/define/config.go
index 900a363d8..c43601554 100644
--- a/libpod/define/config.go
+++ b/libpod/define/config.go
@@ -75,3 +75,10 @@ const JSONLogging = "json-file"
 
 // NoLogging is the string conmon expects when specifying to use no log driver whatsoever
 const NoLogging = "none"
+
+// Strings used for --sdnotify option to podman
+const (
+	SdNotifyModeContainer = "container"
+	SdNotifyModeConmon    = "conmon"
+	SdNotifyModeIgnore    = "ignore"
+)